(1) Field of the Invention
The present invention is directed to locks and particularly to side bar type locks. Specifically, the present invention relates to enhancing the pick resistance of the novel lock of U.S. Pat. No. 4,404,824. Accordingly, the general objects of the present invention are to provide novel and improved devices and methods of such character.
(2) Description of the Prior Art
The above-referenced co-pending application discloses a novel lock wherein the locking mechanism includes resiliently biased and series connected pin tumblers and side bar tumblers. A resiliently biased locking bar having lugs extending therefrom cooperates with the side bars and a slot in the lock cylinder or shell; the locking bar being movable out of engagement with the cylinder with the lugs passing into gates in the side bars when the side bars are moved the appropriate distance by the pin tumblers in response to key insertion. These locks have numerous attributes, including reduced size and comparatively modest production cost, when compared to the prior art.
The locks of U.S. Pat. No. 4,404,824 are, as a consequence of their use of the side bar principle, highly pick-resistant. It is, nevertheless, possible for a highly skilled practitioner to defeat these locks. The foregoing is possible even though the side bars, which are operated by the pin tumblers, will typically be provided with false gates in the form of rectangular notches. Such "picking" was possible partly because each side bar had to travel a comparatively considerable distance before falling into a false gate whereupon further movement of the associated pin tumbler would be prevented.